I purchased a set of inexpensive metric 3/8" drive hex sockets from Harbor Freight. The set had the correct size for the engine mounting hardware ... which, if memory serves me correctly, was 6 mm (but don't hold me to that).https://www.harborfreight.com/6-pc-3...set-69546.html

I also purchased the extended ball tip version when they were on sale for around $9.